Merge c8fb4c17f1 into 2a437685fc

* [chore] Bump tooling versions, bump go -> v1.23.0

* undo silly change

* sign

* bump go version in go.mod

* allow overflow in imaging

* goreleaser deprecation notices

* [chore] Upgrade golangci-lint, ignore existing int overflow warnings

There is a new lint for unchecked int casts. Integer overflows are bad,
but the old code that triggers this lint seems to be perfectly fine.
Instead of disabling the lint entirely for new code as well, grandfather
in existing code.

* fix golangci-lint documentation link

* revert unrelated changes

* revert another unrelated change

* get rid of remaining nolint:gosec

* swagger updates

* apply review feedback

* fix wrong formatting specifier thing

* fix the linter for real

---------

Co-authored-by: tobi <tobi.smethurst@protonmail.com>

CONTRIBUTING.md

@@ -385,7 +385,7 @@ We use [golangci-lint](https://golangci-lint.run/) for linting, which allows us
 
 If you make a PR that doesn't pass the linter, it will be rejected. As such, it's good practice to run the linter locally before pushing or opening a PR.
 
-To do this, first install the linter following the instructions [here](https://golangci-lint.run/usage/install/#local-installation).
+To do this, first install the linter following the instructions [here](https://golangci-lint.run/welcome/install/).
 
 Then, you can run the linter with:
 

docs/admin/settings.md

@@ -167,3 +167,11 @@ Links to the set contact account and/or email address will appear on the footer
 The selected **contact user** must be an active (not suspended) admin and/or moderator on the instance.
 
 If you're on a single-user instance and you give admin privileges to your main account, you can just fill in your own username here; you don't need to make a separate admin account just for this.
+
+### Instance Custom CSS
+
+custom CSS allows you to further customize the way your instance looks when visited through a browser.
+
+This custom CSS will be applied to all pages of your instance. Users themes and CSS still take precedence over this customization.
+
+See the [Custom CSS](./custom_css.md) page for some tips on writing custom CSS for your instance.

docs/api/swagger.yaml

@@ -1550,6 +1550,10 @@ definitions:
                 $ref: '#/definitions/instanceV1Configuration'
             contact_account:
                 $ref: '#/definitions/account'
+            custom_css:
+                description: Custom CSS for the instance.
+                type: string
+                x-go-name: CustomCSS
             debug:
                 description: Whether or not instance is running in DEBUG mode. Omitted if false.
                 type: boolean
@@ -1730,6 +1734,10 @@ definitions:
                 $ref: '#/definitions/instanceV2Configuration'
             contact:
                 $ref: '#/definitions/instanceV2Contact'
+            custom_css:
+                description: Instance Custom Css
+                type: string
+                x-go-name: CustomCSS
             debug:
                 description: Whether or not instance is running in DEBUG mode. Omitted if false.
                 type: boolean
@@ -2114,7 +2122,7 @@ definitions:
             bitrate:
                 description: Bitrate of the media in bits per second.
                 example: 1000000
-                format: int64
+                format: uint64
                 type: integer
                 x-go-name: Bitrate
             duration:

example/apparmor/gotosocial

@@ -24,12 +24,12 @@ profile gotosocial flags=(attach_disconnected, mediate_deleted) {
 
   # Embedded ffmpeg needs read
   # permission on /dev/urandom.
-  owner /dev/ r,
+  /dev/ r,
-  owner /dev/urandom r,
+  /dev/urandom r,
 
   # Temp dir access is needed for storing
   # files briefly during media processing.
-  owner /tmp/ r,
+  /tmp/ r,
   owner /tmp/* rwk,
 
   # If running with GTS_WAZERO_COMPILATION_CACHE set,
@@ -39,7 +39,7 @@ profile gotosocial flags=(attach_disconnected, mediate_deleted) {
 
   # If you've enabled logging to syslog, allow GoToSocial
   # to write logs by uncommenting the following line:
-  # owner /var/log/syslog w,
+  # /var/log/syslog w,
 
   # These directories are not currently used by any of
   # the recommended GoToSocial installation methods, but
@@ -65,6 +65,7 @@ profile gotosocial flags=(attach_disconnected, mediate_deleted) {
   /etc/services r,
   /proc/sys/net/core/somaxconn r,
   /sys/fs/cgroup/system.slice/gotosocial.service/{,*} r,
+  /sys/kernel/mm/hugepages/ r,
   /sys/kernel/mm/transparent_hugepage/hpage_pmd_size r,
   owner /proc/*/cgroup r,
   owner /proc/*/cpuset r,

internal/api/client/admin/emojicreate.go

@@ -145,8 +145,8 @@ func validateCreateEmoji(form *apimodel.EmojiCreateRequest) error {
 		return errors.New("no emoji given")
 	}
 
-	maxSize := config.GetMediaEmojiLocalMaxSize()
+	maxSize := int64(config.GetMediaEmojiLocalMaxSize()) // #nosec G115 -- Already validated.
-	if form.Image.Size > int64(maxSize) {
+	if form.Image.Size > maxSize {
 		return fmt.Errorf("emoji image too large: image is %dKB but size limit for custom emojis is %dKB", form.Image.Size/1024, maxSize/1024)
 	}
 

internal/api/client/admin/emojiupdate.go

@@ -208,8 +208,8 @@ func validateUpdateEmoji(form *apimodel.EmojiUpdateRequest) error {
 		}
 
 		if hasImage {
-			maxSize := config.GetMediaEmojiLocalMaxSize()
+			maxSize := int64(config.GetMediaEmojiLocalMaxSize()) // #nosec G115 -- Already validated.
-			if form.Image.Size > int64(maxSize) {
+			if form.Image.Size > maxSize {
 				return fmt.Errorf("emoji image too large: image is %dKB but size limit for custom emojis is %dKB", form.Image.Size/1024, maxSize/1024)
 			}
 		}

internal/api/client/instance/instancepatch.go

@@ -175,6 +175,7 @@ func validateInstanceUpdate(form *apimodel.InstanceSettingsUpdateRequest) error
 		form.ContactEmail == nil &&
 		form.ShortDescription == nil &&
 		form.Description == nil &&
+		form.CustomCSS == nil &&
 		form.Terms == nil &&
 		form.Avatar == nil &&
 		form.AvatarDescription == nil &&

internal/api/model/attachment.go

@@ -160,7 +160,7 @@ type MediaDimensions struct {
 	Duration float32 `json:"duration,omitempty"`
 	// Bitrate of the media in bits per second.
 	// example: 1000000
-	Bitrate int `json:"bitrate,omitempty"`
+	Bitrate uint64 `json:"bitrate,omitempty"`
 	// Size of the media, in the format `[width]x[height]`.
 	// Not set for audio.
 	// example: 1920x1080

internal/api/model/instance.go

@@ -33,6 +33,8 @@ type InstanceSettingsUpdateRequest struct {
 	ShortDescription *string `form:"short_description" json:"short_description" xml:"short_description"`
 	// Longer description of the instance, max 5,000 chars. HTML formatting accepted.
 	Description *string `form:"description" json:"description" xml:"description"`
+	// Custom CSS for the instance.
+	CustomCSS *string `form:"custom_css" json:"custom_css,omitempty" xml:"custom_css"`
 	// Terms and conditions of the instance, max 5,000 chars. HTML formatting accepted.
 	Terms *string `form:"terms" json:"terms" xml:"terms"`
 	// Image to use as the instance thumbnail.

internal/api/model/instancev1.go

@@ -38,6 +38,8 @@ type InstanceV1 struct {
 	//
 	// This should be displayed on the 'about' page for an instance.
 	Description string `json:"description"`
+	// Custom CSS for the instance.
+	CustomCSS string `json:"custom_css,omitempty"`
 	// Raw (unparsed) version of description.
 	DescriptionText string `json:"description_text,omitempty"`
 	// A shorter description of the instance.

internal/api/model/instancev2.go

@@ -53,6 +53,8 @@ type InstanceV2 struct {
 	Description string `json:"description"`
 	// Raw (unparsed) version of description.
 	DescriptionText string `json:"description_text,omitempty"`
+	// Instance Custom Css
+	CustomCSS string `json:"custom_css,omitempty"`
 	// Basic anonymous usage data for this instance.
 	Usage InstanceV2Usage `json:"usage"`
 	// An image used to represent this instance.

internal/cache/domain/domain.go

@@ -220,7 +220,7 @@ func (n *node) getChild(part string) *node {
 
 	for i < j {
 		// avoid overflow when computing h
-		h := int(uint(i+j) >> 1)
+		h := int(uint(i+j) >> 1) // #nosec G115
 		// i ≤ h < j
 
 		if n.child[h].part < part {

internal/db/bundb/bundb.go

@@ -25,6 +25,7 @@
 	"encoding/pem"
 	"errors"
 	"fmt"
+	"math"
 	"net/url"
 	"os"
 	"runtime"
@@ -489,7 +490,10 @@ func deriveBunDBPGOptions() (*pgx.ConnConfig, error) {
 		cfg.Host = address
 	}
 	if port := config.GetDbPort(); port > 0 {
-		cfg.Port = uint16(port)
+		if port > math.MaxUint16 {
+			return nil, errors.New("invalid port, must be in range 1-65535")
+		}
+		cfg.Port = uint16(port) // #nosec G115 -- Just validated above.
 	}
 	if u := config.GetDbUser(); u != "" {
 		cfg.User = u

internal/db/bundb/migrations/20240924222938_add_instance_custom_css.go

@@ -0,0 +1,44 @@
+// GoToSocial
+// Copyright (C) GoToSocial Authors admin@gotosocial.org
+// SPDX-License-Identifier: AGPL-3.0-or-later
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package migrations
+
+import (
+	"context"
+	"strings"
+
+	"github.com/uptrace/bun"
+)
+
+func init() {
+	up := func(ctx context.Context, db *bun.DB) error {
+		_, err := db.ExecContext(ctx, "ALTER TABLE ? ADD COLUMN ? TEXT", bun.Ident("instances"), bun.Ident("custom_css"))
+		if err != nil && !(strings.Contains(err.Error(), "already exists") || strings.Contains(err.Error(), "duplicate column name") || strings.Contains(err.Error(), "SQLSTATE 42701")) {
+			return err
+		}
+		return nil
+	}
+
+	down := func(ctx context.Context, db *bun.DB) error {
+		_, err := db.ExecContext(ctx, "ALTER TABLE ? DROP COLUMN ?", bun.Ident("instances"), bun.Ident("custom_css"))
+		return err
+	}
+
+	if err := Migrations.Register(up, down); err != nil {
+		panic(err)
+	}
+}

internal/federation/dereferencing/emoji.go

@@ -97,11 +97,11 @@ func() (*media.ProcessingEmoji, error) {
 			}
 
 			// Get maximum supported remote emoji size.
-			maxsz := config.GetMediaEmojiRemoteMaxSize()
+			maxsz := int64(config.GetMediaEmojiRemoteMaxSize()) // #nosec G115 -- Already validated.
 
 			// Prepare data function to dereference remote emoji media.
 			data := func(context.Context) (io.ReadCloser, error) {
-				return tsport.DereferenceMedia(ctx, url, int64(maxsz))
+				return tsport.DereferenceMedia(ctx, url, maxsz)
 			}
 
 			// Create new emoji with prepared info.
@@ -189,11 +189,11 @@ func() (*media.ProcessingEmoji, error) {
 			}
 
 			// Get maximum supported remote emoji size.
-			maxsz := config.GetMediaEmojiRemoteMaxSize()
+			maxsz := int64(config.GetMediaEmojiRemoteMaxSize()) // #nosec G115 -- Already validated.
 
 			// Prepare data function to dereference remote emoji media.
 			data := func(context.Context) (io.ReadCloser, error) {
-				return tsport.DereferenceMedia(ctx, url, int64(maxsz))
+				return tsport.DereferenceMedia(ctx, url, maxsz)
 			}
 
 			// Update emoji with prepared info.
@@ -255,11 +255,11 @@ func() (*media.ProcessingEmoji, error) {
 			}
 
 			// Get maximum supported remote emoji size.
-			maxsz := config.GetMediaEmojiRemoteMaxSize()
+			maxsz := int64(config.GetMediaEmojiRemoteMaxSize()) // #nosec G115 -- Already validated.
 
 			// Prepare data function to dereference remote emoji media.
 			data := func(context.Context) (io.ReadCloser, error) {
-				return tsport.DereferenceMedia(ctx, url, int64(maxsz))
+				return tsport.DereferenceMedia(ctx, url, maxsz)
 			}
 
 			// Recache emoji with prepared info.

internal/federation/dereferencing/media.go

@@ -77,14 +77,14 @@ func() (*media.ProcessingMedia, error) {
 			}
 
 			// Get maximum supported remote media size.
-			maxsz := config.GetMediaRemoteMaxSize()
+			maxsz := int64(config.GetMediaRemoteMaxSize()) // #nosec G115 -- Already validated.
 
 			// Create media with prepared info.
 			return d.mediaManager.CreateMedia(
 				ctx,
 				accountID,
 				func(ctx context.Context) (io.ReadCloser, error) {
-					return tsport.DereferenceMedia(ctx, url, int64(maxsz))
+					return tsport.DereferenceMedia(ctx, url, maxsz)
 				},
 				info,
 			)
@@ -168,14 +168,14 @@ func() (*media.ProcessingMedia, error) {
 			}
 
 			// Get maximum supported remote media size.
-			maxsz := config.GetMediaRemoteMaxSize()
+			maxsz := int64(config.GetMediaRemoteMaxSize()) // #nosec G115 -- Already validated.
 
 			// Recache media with prepared info,
 			// this will also update media in db.
 			return d.mediaManager.CacheMedia(
 				attach,
 				func(ctx context.Context) (io.ReadCloser, error) {
-					return tsport.DereferenceMedia(ctx, url, int64(maxsz))
+					return tsport.DereferenceMedia(ctx, url, maxsz)
 				},
 			), nil
 		},

internal/gtsmodel/instance.go

@@ -34,6 +34,7 @@ type Instance struct {
 	ShortDescriptionText   string       `bun:""`                                                            // Raw text version of short description (before parsing).
 	Description            string       `bun:""`                                                            // Longer description of this instance.
 	DescriptionText        string       `bun:""`                                                            // Raw text version of long description (before parsing).
+	CustomCSS              string       `bun:",nullzero"`                                                   // Custom CSS for the instance.
 	Terms                  string       `bun:""`                                                            // Terms and conditions of this instance.
 	TermsText              string       `bun:""`                                                            // Raw text version of terms (before parsing).
 	ContactEmail           string       `bun:""`                                                            // Contact email address for this instance

internal/httpclient/client.go

@@ -340,14 +340,14 @@ func (c *Client) do(r *Request) (rsp *http.Response, retry bool, err error) {
 
 			if u, _ := strconv.ParseUint(after, 10, 32); u != 0 {
 				// An integer no. of backoff seconds was provided.
-				r.backoff = time.Duration(u) * time.Second
+				r.backoff = time.Duration(u) * time.Second // #nosec G115 -- We clamp backoff below.
 			} else if at, _ := http.ParseTime(after); !at.Before(now) {
 				// An HTTP formatted future date-time was provided.
 				r.backoff = at.Sub(now)
 			}
 
 			// Don't let their provided backoff exceed our max.
-			if max := baseBackoff * time.Duration(c.retries); //
+			if max := baseBackoff * time.Duration(c.retries); // #nosec G115 -- We control c.retries.
 			r.backoff > max {
 				r.backoff = max
 			}

internal/media/ffmpeg.go

@@ -556,10 +556,10 @@ func (res *ffprobeResult) Process() (*result, error) {
 				if p := strings.SplitN(str, "/", 2); len(p) == 2 {
 					n, _ := strconv.ParseUint(p[0], 10, 32)
 					d, _ := strconv.ParseUint(p[1], 10, 32)
-					num, den = uint32(n), uint32(d)
+					num, den = uint32(n), uint32(d) // #nosec G115 -- ParseUint is configured to check
 				} else {
 					n, _ := strconv.ParseUint(p[0], 10, 32)
-					num = uint32(n)
+					num = uint32(n) // #nosec G115 -- ParseUint is configured to check
 				}
 
 				// Set final divised framerate.

internal/media/imaging.go

@@ -399,9 +399,9 @@ func (s *scanner) scan(x1, y1, x2, y2 int, dst []uint8) {
 					g16 := uint16(s[1])
 					b16 := uint16(s[2])
 					a16 := uint16(a)
-					d[0] = uint8(r16 * 0xff / a16)
+					d[0] = uint8(r16 * 0xff / a16) // #nosec G115 -- Overflow desired.
-					d[1] = uint8(g16 * 0xff / a16)
+					d[1] = uint8(g16 * 0xff / a16) // #nosec G115 -- Overflow desired.
-					d[2] = uint8(b16 * 0xff / a16)
+					d[2] = uint8(b16 * 0xff / a16) // #nosec G115 -- Overflow desired.
 					d[3] = a
 				}
 				j += 4
@@ -431,9 +431,9 @@ func (s *scanner) scan(x1, y1, x2, y2 int, dst []uint8) {
 					g32 := uint32(s[2])<<8 | uint32(s[3])
 					b32 := uint32(s[4])<<8 | uint32(s[5])
 					a32 := uint32(s[6])<<8 | uint32(s[7])
-					d[0] = uint8((r32 * 0xffff / a32) >> 8)
+					d[0] = uint8((r32 * 0xffff / a32) >> 8) // #nosec G115 -- Overflow desired.
-					d[1] = uint8((g32 * 0xffff / a32) >> 8)
+					d[1] = uint8((g32 * 0xffff / a32) >> 8) // #nosec G115 -- Overflow desired.
-					d[2] = uint8((b32 * 0xffff / a32) >> 8)
+					d[2] = uint8((b32 * 0xffff / a32) >> 8) // #nosec G115 -- Overflow desired.
 				}
 				d[3] = a
 				j += 4
@@ -509,30 +509,30 @@ func (s *scanner) scan(x1, y1, x2, y2 int, dst []uint8) {
 				cr1 := int32(img.Cr[ic]) - 128
 
 				r := yy1 + 91881*cr1
-				if uint32(r)&0xff000000 == 0 {
+				if uint32(r)&0xff000000 == 0 { //nolint:gosec
 					r >>= 16
 				} else {
 					r = ^(r >> 31)
 				}
 
 				g := yy1 - 22554*cb1 - 46802*cr1
-				if uint32(g)&0xff000000 == 0 {
+				if uint32(g)&0xff000000 == 0 { //nolint:gosec
 					g >>= 16
 				} else {
 					g = ^(g >> 31)
 				}
 
 				b := yy1 + 116130*cb1
-				if uint32(b)&0xff000000 == 0 {
+				if uint32(b)&0xff000000 == 0 { //nolint:gosec
 					b >>= 16
 				} else {
 					b = ^(b >> 31)
 				}
 
 				d := dst[j : j+4 : j+4]
-				d[0] = uint8(r)
+				d[0] = uint8(r) // #nosec G115 -- Overflow desired.
-				d[1] = uint8(g)
+				d[1] = uint8(g) // #nosec G115 -- Overflow desired.
-				d[2] = uint8(b)
+				d[2] = uint8(b) // #nosec G115 -- Overflow desired.
 				d[3] = 0xff
 
 				iy++
@@ -569,9 +569,9 @@ func (s *scanner) scan(x1, y1, x2, y2 int, dst []uint8) {
 				d := dst[j : j+4 : j+4]
 				switch a16 {
 				case 0xffff:
-					d[0] = uint8(r16 >> 8)
+					d[0] = uint8(r16 >> 8) // #nosec G115 -- Overflow desired.
-					d[1] = uint8(g16 >> 8)
+					d[1] = uint8(g16 >> 8) // #nosec G115 -- Overflow desired.
-					d[2] = uint8(b16 >> 8)
+					d[2] = uint8(b16 >> 8) // #nosec G115 -- Overflow desired.
 					d[3] = 0xff
 				case 0:
 					d[0] = 0
@@ -579,10 +579,10 @@ func (s *scanner) scan(x1, y1, x2, y2 int, dst []uint8) {
 					d[2] = 0
 					d[3] = 0
 				default:
-					d[0] = uint8(((r16 * 0xffff) / a16) >> 8)
+					d[0] = uint8(((r16 * 0xffff) / a16) >> 8) // #nosec G115 -- Overflow desired.
-					d[1] = uint8(((g16 * 0xffff) / a16) >> 8)
+					d[1] = uint8(((g16 * 0xffff) / a16) >> 8) // #nosec G115 -- Overflow desired.
-					d[2] = uint8(((b16 * 0xffff) / a16) >> 8)
+					d[2] = uint8(((b16 * 0xffff) / a16) >> 8) // #nosec G115 -- Overflow desired.
-					d[3] = uint8(a16 >> 8)
+					d[3] = uint8(a16 >> 8)                    // #nosec G115 -- Overflow desired.
 				}
 				j += 4
 			}
@@ -617,7 +617,7 @@ func clampFloat(x float64) uint8 {
 		return 255
 	}
 	if v > 0 {
-		return uint8(v)
+		return uint8(v) // #nosec G115 -- Just checked.
 	}
 	return 0
 }

internal/media/refetch.go

@@ -49,9 +49,6 @@ func (m *Manager) RefetchEmojis(ctx context.Context, domain string, dereferenceM
 		refetchIDs         []string
 	)
 
-	// Get max supported remote emoji media size.
-	maxsz := config.GetMediaEmojiRemoteMaxSize()
-
 	// page through emojis 20 at a time, looking for those with missing images
 	for {
 		// Fetch next block of emojis from database
@@ -111,8 +108,10 @@ func (m *Manager) RefetchEmojis(ctx context.Context, domain string, dereferenceM
 			continue
 		}
 
+		// Get max supported remote emoji media size.
+		maxsz := int64(config.GetMediaEmojiRemoteMaxSize()) // #nosec G115 -- Already validated.
 		dataFunc := func(ctx context.Context) (reader io.ReadCloser, err error) {
-			return dereferenceMedia(ctx, emojiImageIRI, int64(maxsz))
+			return dereferenceMedia(ctx, emojiImageIRI, maxsz)
 		}
 
 		processingEmoji, err := m.UpdateEmoji(ctx, emoji, dataFunc, AdditionalEmojiInfo{

internal/media/util.go

@@ -145,7 +145,7 @@ func drainToTmp(rc io.ReadCloser) (string, error) {
 	// Check to see if limit was reached,
 	// (produces more useful error messages).
 	if lr != nil && lr.N <= 0 {
-		err := fmt.Errorf("reached read limit %s", bytesize.Size(limit))
+		err := fmt.Errorf("reached read limit %s", bytesize.Size(limit)) // #nosec G115 -- Just logging
 		return path, gtserror.SetLimitReached(err)
 	}
 

internal/middleware/logger.go

@@ -123,7 +123,7 @@ func Logger(logClientIP bool) gin.HandlerFunc {
 			}
 
 			// Generate a nicer looking bytecount
-			size := bytesize.Size(c.Writer.Size())
+			size := bytesize.Size(c.Writer.Size()) // #nosec G115 -- Just logging
 
 			// Finally, write log entry with status text + body size.
 			l.Logf(lvl, "%s: wrote %s", statusText, size)

internal/middleware/requestid.go

@@ -48,7 +48,7 @@ func NewRequestID() string {
 	b := make([]byte, 12)
 
 	// Get current time in milliseconds.
-	ms := uint64(time.Now().UnixMilli())
+	ms := uint64(time.Now().UnixMilli()) // #nosec G115 -- Pre-1970 clock?
 
 	// Store binary time data in byte buffer.
 	binary.LittleEndian.PutUint64(b[0:8], ms)

internal/middleware/throttling.go

@@ -82,12 +82,16 @@ func Throttle(cpuMultiplier int, retryAfter time.Duration) gin.HandlerFunc {
 		return func(c *gin.Context) {}
 	}
 
+	if retryAfter < 0 {
+		retryAfter = 0
+	}
+
 	var (
 		limit         = runtime.GOMAXPROCS(0) * cpuMultiplier
 		queueLimit    = limit * cpuMultiplier
 		tokens        = make(chan token, limit)
 		requestCount  = atomic.Int64{}
-		retryAfterStr = strconv.FormatUint(uint64(retryAfter/time.Second), 10)
+		retryAfterStr = strconv.FormatUint(uint64(retryAfter/time.Second), 10) // #nosec G115 -- Checked right above
 	)
 
 	// prefill token channel

internal/processing/account/update.go

@@ -463,9 +463,10 @@ func (p *Processor) UpdateAvatar(
 ) {
 	// Get maximum supported local media size.
 	maxsz := config.GetMediaLocalMaxSize()
+	maxszInt64 := int64(maxsz) // #nosec G115 -- Already validated.
 
 	// Ensure media within size bounds.
-	if avatar.Size > int64(maxsz) {
+	if avatar.Size > maxszInt64 {
 		text := fmt.Sprintf("media exceeds configured max size: %s", maxsz)
 		return nil, gtserror.NewErrorBadRequest(errors.New(text), text)
 	}
@@ -478,7 +479,7 @@ func (p *Processor) UpdateAvatar(
 	}
 
 	// Wrap the multipart file reader to ensure is limited to max.
-	rc, _, _ := iotools.UpdateReadCloserLimit(mpfile, int64(maxsz))
+	rc, _, _ := iotools.UpdateReadCloserLimit(mpfile, maxszInt64)
 
 	// Write to instance storage.
 	return p.c.StoreLocalMedia(ctx,
@@ -508,9 +509,10 @@ func (p *Processor) UpdateHeader(
 ) {
 	// Get maximum supported local media size.
 	maxsz := config.GetMediaLocalMaxSize()
+	maxszInt64 := int64(maxsz) // #nosec G115 -- Already validated.
 
 	// Ensure media within size bounds.
-	if header.Size > int64(maxsz) {
+	if header.Size > maxszInt64 {
 		text := fmt.Sprintf("media exceeds configured max size: %s", maxsz)
 		return nil, gtserror.NewErrorBadRequest(errors.New(text), text)
 	}
@@ -523,7 +525,7 @@ func (p *Processor) UpdateHeader(
 	}
 
 	// Wrap the multipart file reader to ensure is limited to max.
-	rc, _, _ := iotools.UpdateReadCloserLimit(mpfile, int64(maxsz))
+	rc, _, _ := iotools.UpdateReadCloserLimit(mpfile, maxszInt64)
 
 	// Write to instance storage.
 	return p.c.StoreLocalMedia(ctx,

internal/processing/admin/emoji.go

@@ -25,7 +25,6 @@
 	"mime/multipart"
 	"strings"
 
-	"codeberg.org/gruf/go-bytesize"
 	"codeberg.org/gruf/go-iotools"
 	apimodel "github.com/superseriousbusiness/gotosocial/internal/api/model"
 	"github.com/superseriousbusiness/gotosocial/internal/config"
@@ -46,9 +45,10 @@ func (p *Processor) EmojiCreate(
 
 	// Get maximum supported local emoji size.
 	maxsz := config.GetMediaEmojiLocalMaxSize()
+	maxszInt64 := int64(maxsz) // #nosec G115 -- Already validated.
 
 	// Ensure media within size bounds.
-	if form.Image.Size > int64(maxsz) {
+	if form.Image.Size > maxszInt64 {
 		text := fmt.Sprintf("emoji exceeds configured max size: %s", maxsz)
 		return nil, gtserror.NewErrorBadRequest(errors.New(text), text)
 	}
@@ -61,7 +61,7 @@ func (p *Processor) EmojiCreate(
 	}
 
 	// Wrap the multipart file reader to ensure is limited to max.
-	rc, _, _ := iotools.UpdateReadCloserLimit(mpfile, int64(maxsz))
+	rc, _, _ := iotools.UpdateReadCloserLimit(mpfile, maxszInt64)
 	data := func(context.Context) (io.ReadCloser, error) {
 		return rc, nil
 	}
@@ -301,9 +301,10 @@ func (p *Processor) emojiUpdateCopy(
 
 	// Get maximum supported local emoji size.
 	maxsz := config.GetMediaEmojiLocalMaxSize()
+	maxszInt := int(maxsz) // #nosec G115 -- Already validated.
 
 	// Ensure target emoji image within size bounds.
-	if bytesize.Size(target.ImageFileSize) > maxsz {
+	if target.ImageFileSize > maxszInt {
 		text := fmt.Sprintf("emoji exceeds configured max size: %s", maxsz)
 		return nil, gtserror.NewErrorBadRequest(errors.New(text), text)
 	}
@@ -442,9 +443,10 @@ func (p *Processor) emojiUpdateModify(
 
 		// Get maximum supported local emoji size.
 		maxsz := config.GetMediaEmojiLocalMaxSize()
+		maxszInt64 := int64(maxsz) // #nosec G115 -- Already validated.
 
 		// Ensure media within size bounds.
-		if image.Size > int64(maxsz) {
+		if image.Size > maxszInt64 {
 			text := fmt.Sprintf("emoji exceeds configured max size: %s", maxsz)
 			return nil, gtserror.NewErrorBadRequest(errors.New(text), text)
 		}
@@ -457,7 +459,7 @@ func (p *Processor) emojiUpdateModify(
 		}
 
 		// Wrap the multipart file reader to ensure is limited to max.
-		rc, _, _ := iotools.UpdateReadCloserLimit(mpfile, int64(maxsz))
+		rc, _, _ := iotools.UpdateReadCloserLimit(mpfile, int64(maxsz)) // #nosec G115 -- Already validated.
 		data := func(context.Context) (io.ReadCloser, error) {
 			return rc, nil
 		}

internal/processing/instance.go

@@ -227,6 +227,17 @@ func (p *Processor) InstancePatch(ctx context.Context, form *apimodel.InstanceSe
 		columns = append(columns, []string{"description", "description_text"}...)
 	}
 
+	// validate & update site custom css if it's set on the form
+	if form.CustomCSS != nil {
+		customCSS := *form.CustomCSS
+		if err := validate.InstanceCustomCSS(customCSS); err != nil {
+			return nil, gtserror.NewErrorBadRequest(err, err.Error())
+		}
+
+		instance.CustomCSS = text.SanitizeToPlaintext(customCSS)
+		columns = append(columns, []string{"custom_css"}...)
+	}
+
 	// Validate & update site
 	// terms if set on the form.
 	if form.Terms != nil {

internal/processing/media/create.go

@@ -36,9 +36,10 @@ func (p *Processor) Create(ctx context.Context, account *gtsmodel.Account, form
 
 	// Get maximum supported local media size.
 	maxsz := config.GetMediaLocalMaxSize()
+	maxszInt64 := int64(maxsz) // #nosec G115 -- Already validated.
 
 	// Ensure media within size bounds.
-	if form.File.Size > int64(maxsz) {
+	if form.File.Size > maxszInt64 {
 		text := fmt.Sprintf("media exceeds configured max size: %s", maxsz)
 		return nil, gtserror.NewErrorBadRequest(errors.New(text), text)
 	}
@@ -58,7 +59,7 @@ func (p *Processor) Create(ctx context.Context, account *gtsmodel.Account, form
 	}
 
 	// Wrap the multipart file reader to ensure is limited to max.
-	rc, _, _ := iotools.UpdateReadCloserLimit(mpfile, int64(maxsz))
+	rc, _, _ := iotools.UpdateReadCloserLimit(mpfile, maxszInt64)
 
 	// Create local media and write to instance storage.
 	attachment, errWithCode := p.c.StoreLocalMedia(ctx,

internal/transport/derefmedia.go

@@ -53,7 +53,7 @@ func (t *transport) DereferenceMedia(ctx context.Context, iri *url.URL, maxsz in
 	// Check media within size limit.
 	if rsp.ContentLength > maxsz {
 		_ = rsp.Body.Close()       // close early.
-		sz := bytesize.Size(maxsz) // nicer log format
+		sz := bytesize.Size(maxsz) //nolint:gosec
 		return nil, gtserror.Newf("media body exceeds max size %s", sz)
 	}
 

internal/typeutils/internaltofrontend.go

@@ -647,7 +647,7 @@ func (c *Converter) AttachmentToAPIAttachment(ctx context.Context, media *gtsmod
 			Size:      toAPISize(media.FileMeta.Original.Width, media.FileMeta.Original.Height),
 			FrameRate: toAPIFrameRate(media.FileMeta.Original.Framerate),
 			Duration:  util.PtrOrZero(media.FileMeta.Original.Duration),
-			Bitrate:   int(util.PtrOrZero(media.FileMeta.Original.Bitrate)),
+			Bitrate:   util.PtrOrZero(media.FileMeta.Original.Bitrate),
 		}
 
 		// Copy over local file URL.
@@ -1523,15 +1523,16 @@ func (c *Converter) InstanceToAPIV1Instance(ctx context.Context, i *gtsmodel.Ins
 		Title:                i.Title,
 		Description:          i.Description,
 		DescriptionText:      i.DescriptionText,
+		CustomCSS:            i.CustomCSS,
 		ShortDescription:     i.ShortDescription,
 		ShortDescriptionText: i.ShortDescriptionText,
 		Email:                i.ContactEmail,
 		Version:              config.GetSoftwareVersion(),
 		Languages:            config.GetInstanceLanguages().TagStrs(),
 		Registrations:        config.GetAccountsRegistrationOpen(),
-		ApprovalRequired:     true,  // approval always required
+		ApprovalRequired:     true,                               // approval always required
-		InvitesEnabled:       false, // todo: not supported yet
+		InvitesEnabled:       false,                              // todo: not supported yet
-		MaxTootChars:         uint(config.GetStatusesMaxChars()),
+		MaxTootChars:         uint(config.GetStatusesMaxChars()), // #nosec G115 -- Already validated.
 		Rules:                c.InstanceRulesToAPIRules(i.Rules),
 		Terms:                i.Terms,
 		TermsRaw:             i.TermsText,
@@ -1551,9 +1552,9 @@ func (c *Converter) InstanceToAPIV1Instance(ctx context.Context, i *gtsmodel.Ins
 	instance.Configuration.Statuses.CharactersReservedPerURL = instanceStatusesCharactersReservedPerURL
 	instance.Configuration.Statuses.SupportedMimeTypes = instanceStatusesSupportedMimeTypes
 	instance.Configuration.MediaAttachments.SupportedMimeTypes = media.SupportedMIMETypes
-	instance.Configuration.MediaAttachments.ImageSizeLimit = int(config.GetMediaRemoteMaxSize())
+	instance.Configuration.MediaAttachments.ImageSizeLimit = int(config.GetMediaRemoteMaxSize()) // #nosec G115 -- Already validated.
 	instance.Configuration.MediaAttachments.ImageMatrixLimit = instanceMediaAttachmentsImageMatrixLimit
-	instance.Configuration.MediaAttachments.VideoSizeLimit = int(config.GetMediaRemoteMaxSize())
+	instance.Configuration.MediaAttachments.VideoSizeLimit = int(config.GetMediaRemoteMaxSize()) // #nosec G115 -- Already validated.
 	instance.Configuration.MediaAttachments.VideoFrameRateLimit = instanceMediaAttachmentsVideoFrameRateLimit
 	instance.Configuration.MediaAttachments.VideoMatrixLimit = instanceMediaAttachmentsVideoMatrixLimit
 	instance.Configuration.Polls.MaxOptions = config.GetStatusesPollMaxOptions()
@@ -1563,7 +1564,7 @@ func (c *Converter) InstanceToAPIV1Instance(ctx context.Context, i *gtsmodel.Ins
 	instance.Configuration.Accounts.AllowCustomCSS = config.GetAccountsAllowCustomCSS()
 	instance.Configuration.Accounts.MaxFeaturedTags = instanceAccountsMaxFeaturedTags
 	instance.Configuration.Accounts.MaxProfileFields = instanceAccountsMaxProfileFields
-	instance.Configuration.Emojis.EmojiSizeLimit = int(config.GetMediaEmojiLocalMaxSize())
+	instance.Configuration.Emojis.EmojiSizeLimit = int(config.GetMediaEmojiLocalMaxSize()) // #nosec G115 -- Already validated.
 	instance.Configuration.OIDCEnabled = config.GetOIDCEnabled()
 
 	// URLs
@@ -1644,6 +1645,7 @@ func (c *Converter) InstanceToAPIV2Instance(ctx context.Context, i *gtsmodel.Ins
 		SourceURL:       instanceSourceURL,
 		Description:     i.Description,
 		DescriptionText: i.DescriptionText,
+		CustomCSS:       i.CustomCSS,
 		Usage:           apimodel.InstanceV2Usage{}, // todo: not implemented
 		Languages:       config.GetInstanceLanguages().TagStrs(),
 		Rules:           c.InstanceRulesToAPIRules(i.Rules),
@@ -1695,9 +1697,9 @@ func (c *Converter) InstanceToAPIV2Instance(ctx context.Context, i *gtsmodel.Ins
 	instance.Configuration.Statuses.CharactersReservedPerURL = instanceStatusesCharactersReservedPerURL
 	instance.Configuration.Statuses.SupportedMimeTypes = instanceStatusesSupportedMimeTypes
 	instance.Configuration.MediaAttachments.SupportedMimeTypes = media.SupportedMIMETypes
-	instance.Configuration.MediaAttachments.ImageSizeLimit = int(config.GetMediaRemoteMaxSize())
+	instance.Configuration.MediaAttachments.ImageSizeLimit = int(config.GetMediaRemoteMaxSize()) // #nosec G115 -- Already validated.
 	instance.Configuration.MediaAttachments.ImageMatrixLimit = instanceMediaAttachmentsImageMatrixLimit
-	instance.Configuration.MediaAttachments.VideoSizeLimit = int(config.GetMediaRemoteMaxSize())
+	instance.Configuration.MediaAttachments.VideoSizeLimit = int(config.GetMediaRemoteMaxSize()) // #nosec G115 -- Already validated.
 	instance.Configuration.MediaAttachments.VideoFrameRateLimit = instanceMediaAttachmentsVideoFrameRateLimit
 	instance.Configuration.MediaAttachments.VideoMatrixLimit = instanceMediaAttachmentsVideoMatrixLimit
 	instance.Configuration.Polls.MaxOptions = config.GetStatusesPollMaxOptions()
@@ -1707,7 +1709,7 @@ func (c *Converter) InstanceToAPIV2Instance(ctx context.Context, i *gtsmodel.Ins
 	instance.Configuration.Accounts.AllowCustomCSS = config.GetAccountsAllowCustomCSS()
 	instance.Configuration.Accounts.MaxFeaturedTags = instanceAccountsMaxFeaturedTags
 	instance.Configuration.Accounts.MaxProfileFields = instanceAccountsMaxProfileFields
-	instance.Configuration.Emojis.EmojiSizeLimit = int(config.GetMediaEmojiLocalMaxSize())
+	instance.Configuration.Emojis.EmojiSizeLimit = int(config.GetMediaEmojiLocalMaxSize()) // #nosec G115 -- Already validated.
 	instance.Configuration.OIDCEnabled = config.GetOIDCEnabled()
 
 	// registrations

internal/validate/formvalidation.go

@@ -189,6 +189,16 @@ func CustomCSS(customCSS string) error {
 	return nil
 }
 
+func InstanceCustomCSS(customCSS string) error {
+
+	maximumCustomCSSLength := config.GetAccountsCustomCSSLength()
+	if length := len([]rune(customCSS)); length > maximumCustomCSSLength {
+		return fmt.Errorf("custom_css must be less than %d characters, but submitted custom_css was %d characters", maximumCustomCSSLength, length)
+	}
+
+	return nil
+}
+
 // EmojiShortcode just runs the given shortcode through the regular expression
 // for emoji shortcodes, to figure out whether it's a valid shortcode, ie., 2-30 characters,
 // a-zA-Z, numbers, and underscores.

internal/web/about.go

@@ -54,7 +54,7 @@ func (m *Module) aboutGETHandler(c *gin.Context) {
 		Template:    "about.tmpl",
 		Instance:    instance,
 		OGMeta:      apiutil.OGBase(instance),
-		Stylesheets: []string{cssAbout},
+		Stylesheets: []string{cssAbout, instanceCustomCSSPath},
 		Extra: map[string]any{
 			"showStrap":        true,
 			"blocklistExposed": config.GetInstanceExposeSuspendedWeb(),

internal/web/confirmemail.go

@@ -127,8 +127,9 @@ func (m *Module) confirmEmailPOSTHandler(c *gin.Context) {
 	// Serve page informing user that their
 	// email address is now confirmed.
 	page := apiutil.WebPage{
-		Template: "confirmed_email.tmpl",
+		Template:    "confirmed_email.tmpl",
-		Instance: instance,
+		Instance:    instance,
+		Stylesheets: []string{instanceCustomCSSPath},
 		Extra: map[string]any{
 			"email":    user.Email,
 			"username": user.Account.Username,

internal/web/customcss.go

@@ -55,3 +55,22 @@ func (m *Module) customCSSGETHandler(c *gin.Context) {
 	c.Header(cacheControlHeader, cacheControlNoCache)
 	c.Data(http.StatusOK, textCSSUTF8, []byte(customCSS))
 }
+
+func (m *Module) instanceCustomCSSGETHandler(c *gin.Context) {
+
+	if _, err := apiutil.NegotiateAccept(c, apiutil.TextCSS); err != nil {
+		apiutil.WebErrorHandler(c, gtserror.NewErrorNotAcceptable(err, err.Error()), m.processor.InstanceGetV1)
+		return
+	}
+
+	instanceV1, errWithCode := m.processor.InstanceGetV1(c.Request.Context())
+	if errWithCode != nil {
+		apiutil.WebErrorHandler(c, errWithCode, m.processor.InstanceGetV1)
+		return
+	}
+
+	instanceCustomCSS := instanceV1.CustomCSS
+
+	c.Header(cacheControlHeader, cacheControlNoCache)
+	c.Data(http.StatusOK, textCSSUTF8, []byte(instanceCustomCSS))
+}

internal/web/domain-blocklist.go

@@ -67,7 +67,7 @@ func (m *Module) domainBlockListGETHandler(c *gin.Context) {
 		Template:    "domain-blocklist.tmpl",
 		Instance:    instance,
 		OGMeta:      apiutil.OGBase(instance),
-		Stylesheets: []string{cssFA},
+		Stylesheets: []string{cssFA, instanceCustomCSSPath},
 		Javascript:  []string{jsFrontend},
 		Extra:       map[string]any{"blocklist": domainBlocks},
 	}

internal/web/index.go

@@ -59,7 +59,7 @@ func (m *Module) indexHandler(c *gin.Context) {
 		Template:    "index.tmpl",
 		Instance:    instance,
 		OGMeta:      apiutil.OGBase(instance),
-		Stylesheets: []string{cssAbout, cssIndex},
+		Stylesheets: []string{cssAbout, cssIndex, instanceCustomCSSPath},
 		Extra:       map[string]any{"showStrap": true},
 	}
 

internal/web/profile.go

@@ -132,7 +132,7 @@ func (m *Module) profileGETHandler(c *gin.Context) {
 	}
 
 	// Prepare stylesheets for profile.
-	stylesheets := make([]string, 0, 6)
+	stylesheets := make([]string, 0, 7)
 
 	// Basic profile stylesheets.
 	stylesheets = append(
@@ -142,6 +142,7 @@ func (m *Module) profileGETHandler(c *gin.Context) {
 			cssStatus,
 			cssThread,
 			cssProfile,
+			instanceCustomCSSPath,
 		}...,
 	)
 

internal/web/settings-panel.go

@@ -53,6 +53,7 @@ func (m *Module) SettingsPanelHandler(c *gin.Context) {
 			cssProfile, // Used for rendering stub/fake profiles.
 			cssStatus,  // Used for rendering stub/fake statuses.
 			cssSettings,
+			instanceCustomCSSPath,
 		},
 		Javascript: []string{jsSettings},
 	}

internal/web/signup.go

@@ -126,9 +126,10 @@ func (m *Module) signupPOSTHandler(c *gin.Context) {
 	// Serve a page informing the
 	// user that they've signed up.
 	page := apiutil.WebPage{
-		Template: "signed-up.tmpl",
+		Template:    "signed-up.tmpl",
-		Instance: instance,
+		Instance:    instance,
-		OGMeta:   apiutil.OGBase(instance),
+		Stylesheets: []string{instanceCustomCSSPath},
+		OGMeta:      apiutil.OGBase(instance),
 		Extra: map[string]any{
 			"email":    user.UnconfirmedEmail,
 			"username": user.Account.Username,

internal/web/tag.go

@@ -59,7 +59,7 @@ func (m *Module) tagGETHandler(c *gin.Context) {
 		Template:    "tag.tmpl",
 		Instance:    instance,
 		OGMeta:      apiutil.OGBase(instance),
-		Stylesheets: []string{cssFA, cssThread, cssTag},
+		Stylesheets: []string{cssFA, cssThread, cssTag, instanceCustomCSSPath},
 		Extra:       map[string]any{"tagName": tagName},
 	}
 

internal/web/thread.go

@@ -115,7 +115,7 @@ func (m *Module) threadGETHandler(c *gin.Context) {
 	}
 
 	// Prepare stylesheets for thread.
-	stylesheets := make([]string, 0, 5)
+	stylesheets := make([]string, 0, 6)
 
 	// Basic thread stylesheets.
 	stylesheets = append(
@@ -131,6 +131,7 @@ func (m *Module) threadGETHandler(c *gin.Context) {
 	if theme := targetAccount.Theme; theme != "" {
 		stylesheets = append(
 			stylesheets,
+			instanceCustomCSSPath,
 			themesPathPrefix+"/"+theme,
 		)
 	}

internal/web/web.go

@@ -36,20 +36,21 @@
 )
 
 const (
-	confirmEmailPath   = "/" + uris.ConfirmEmailPath
+	confirmEmailPath      = "/" + uris.ConfirmEmailPath
-	profileGroupPath   = "/@:username"
+	profileGroupPath      = "/@:username"
-	statusPath         = "/statuses/:" + apiutil.WebStatusIDKey // leave out the '/@:username' prefix as this will be served within the profile group
+	statusPath            = "/statuses/:" + apiutil.WebStatusIDKey // leave out the '/@:username' prefix as this will be served within the profile group
-	tagsPath           = "/tags/:" + apiutil.TagNameKey
+	tagsPath              = "/tags/:" + apiutil.TagNameKey
-	customCSSPath      = profileGroupPath + "/custom.css"
+	customCSSPath         = profileGroupPath + "/custom.css"
-	rssFeedPath        = profileGroupPath + "/feed.rss"
+	instanceCustomCSSPath = "/custom.css"
-	assetsPathPrefix   = "/assets"
+	rssFeedPath           = profileGroupPath + "/feed.rss"
-	distPathPrefix     = assetsPathPrefix + "/dist"
+	assetsPathPrefix      = "/assets"
-	themesPathPrefix   = assetsPathPrefix + "/themes"
+	distPathPrefix        = assetsPathPrefix + "/dist"
-	settingsPathPrefix = "/settings"
+	themesPathPrefix      = assetsPathPrefix + "/themes"
-	settingsPanelGlob  = settingsPathPrefix + "/*panel"
+	settingsPathPrefix    = "/settings"
-	userPanelPath      = settingsPathPrefix + "/user"
+	settingsPanelGlob     = settingsPathPrefix + "/*panel"
-	adminPanelPath     = settingsPathPrefix + "/admin"
+	userPanelPath         = settingsPathPrefix + "/user"
-	signupPath         = "/signup"
+	adminPanelPath        = settingsPathPrefix + "/admin"
+	signupPath            = "/signup"
 
 	cacheControlHeader    = "Cache-Control"     // https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Cache-Control
 	cacheControlNoCache   = "no-cache"          // https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Cache-Control#response_directives
@@ -114,6 +115,7 @@ func (m *Module) Route(r *router.Router, mi ...gin.HandlerFunc) {
 	r.AttachHandler(http.MethodGet, settingsPathPrefix, m.SettingsPanelHandler)
 	r.AttachHandler(http.MethodGet, settingsPanelGlob, m.SettingsPanelHandler)
 	r.AttachHandler(http.MethodGet, customCSSPath, m.customCSSGETHandler)
+	r.AttachHandler(http.MethodGet, instanceCustomCSSPath, m.instanceCustomCSSGETHandler)
 	r.AttachHandler(http.MethodGet, rssFeedPath, m.rssFeedGETHandler)
 	r.AttachHandler(http.MethodGet, confirmEmailPath, m.confirmEmailGETHandler)
 	r.AttachHandler(http.MethodPost, confirmEmailPath, m.confirmEmailPOSTHandler)

web/source/settings/lib/types/instance.ts

@@ -25,6 +25,7 @@ export interface InstanceV1 {
     description_text?:       string;
     short_description:      string;
     short_description_text?: string;
+    custom_css:             string;
     email:                  string;
     version:                string;
     debug?:                 boolean;

web/source/settings/views/admin/instance/settings.tsx

@@ -66,6 +66,10 @@ function InstanceSettingsForm({ data: instance }: InstanceSettingsFormProps) {
 			valueSelector: (s: InstanceV1) => s.description_text,
 			validator: (val: string) => val.length <= descLimit ? "" : `Instance description is ${val.length} characters; must be ${descLimit} characters or less`
 		}),
+		customCSS: useTextInput("custom_css", {
+			source: instance,
+			valueSelector: (s: InstanceV1) => s.custom_css
+		}),
 		terms: useTextInput("terms", {
 			source: instance,
 			// Select "raw" text version of parsed field for editing.
@@ -191,6 +195,15 @@ function InstanceSettingsForm({ data: instance }: InstanceSettingsFormProps) {
 				type="email"
 			/>
 
+			<TextArea
+				field={form.customCSS}
+				label={"Custom CSS"}
+				className="monospace"
+				rows={8}
+				autoCapitalize="none"
+				spellCheck="false"
+			/>
+
 			<MutationButton label="Save" result={result} disabled={false} />
 		</form>
 	);