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device/linux-huawei-y530: fix lookup of symbolic links (!856)

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George Hopkins 2020-01-01 17:14:21 +01:00 committed by Alexey Min
parent ddb185b677
commit ef4a30d29c
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GPG key ID: 0B19D2A65870B448
2 changed files with 84 additions and 2 deletions
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80
device/linux-huawei-y530/10_vfs-fix-proc-tid-fdinfo-fd-file-handling.patch Normal file
View file

@ -0,0 +1,80 @@
From 562eac4226c2cf8718b8d87fc947545ccbb6dd20 Mon Sep 17 00:00:00 2001
From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Mon, 4 Jun 2012 11:00:45 -0700
Subject: [PATCH] vfs: Fix /proc/<tid>/fdinfo/<fd> file handling
Cyrill Gorcunov reports that I broke the fdinfo files with commit
30a08bf2d31d ("proc: move fd symlink i_mode calculations into
tid_fd_revalidate()"), and he's quite right.
The tid_fd_revalidate() function is not just used for the <tid>/fd
symlinks, it's also used for the <tid>/fdinfo/<fd> files, and the
permission model for those are different.
So do the dynamic symlink permission handling just for symlinks, making
the fdinfo files once more appear as the proper regular files they are.
Of course, Al Viro argued (probably correctly) that we shouldn't do the
symlink permission games at all, and make the symlinks always just be
the normal 'lrwxrwxrwx'. That would have avoided this issue too, but
since somebody noticed that the permissions had changed (which was the
reason for that original commit 30a08bf2d31d in the first place), people
do apparently use this feature.
[ Basically, you can use the symlink permission data as a cheap "fdinfo"
replacement, since you see whether the file is open for reading and/or
writing by just looking at st_mode of the symlink. So the feature
does make sense, even if the pain it has caused means we probably
shouldn't have done it to begin with. ]
Reported-and-tested-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
fs/proc/base.c | 17 ++++++++++-------
1 file changed, 10 insertions(+), 7 deletions(-)
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 2f198dad..c8cb15dc 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1838,7 +1838,7 @@ static int tid_fd_revalidate(struct dentry *dentry, struct nameidata *nd)
rcu_read_lock();
file = fcheck_files(files, fd);
if (file) {
- unsigned i_mode, f_mode = file->f_mode;
+ unsigned f_mode = file->f_mode;
rcu_read_unlock();
put_files_struct(files);
@@ -1854,12 +1854,14 @@ static int tid_fd_revalidate(struct dentry *dentry, struct nameidata *nd)
inode->i_gid = 0;
}
- i_mode = S_IFLNK;
- if (f_mode & FMODE_READ)
- i_mode |= S_IRUSR | S_IXUSR;
- if (f_mode & FMODE_WRITE)
- i_mode |= S_IWUSR | S_IXUSR;
- inode->i_mode = i_mode;
+ if (S_ISLNK(inode->i_mode)) {
+ unsigned i_mode = S_IFLNK;
+ if (f_mode & FMODE_READ)
+ i_mode |= S_IRUSR | S_IXUSR;
+ if (f_mode & FMODE_WRITE)
+ i_mode |= S_IWUSR | S_IXUSR;
+ inode->i_mode = i_mode;
+ }
security_task_to_inode(task, inode);
put_task_struct(task);
@@ -1894,6 +1896,7 @@ static struct dentry *proc_fd_instantiate(struct inode *dir,
ei = PROC_I(inode);
ei->fd = fd;
+ inode->i_mode = S_IFLNK;
inode->i_op = &proc_pid_link_inode_operations;
inode->i_size = 64;
ei->op.proc_get_link = proc_fd_link;
--
2.17.1

6
device/linux-huawei-y530/APKBUILD
View file

@ -2,7 +2,7 @@
pkgname="linux-huawei-y530"
pkgver=3.4.0
pkgrel=7
pkgrel=8
pkgdesc="Kernel for Huawei MSM8x1x devices"
arch="armv7"
_carch="arm"
@ -39,6 +39,7 @@ source="
07_fix_mdss_fb_refresh_rate.patch
08_fix_touchscreen.patch
09_fix_various_include_directives.patch
10_vfs-fix-proc-tid-fdinfo-fd-file-handling.patch
"
builddir="$srcdir/${_repository}-${_commit}"
@ -121,4 +122,5 @@ fbc61e379403990167853f4c4fbdfa22d7e9661a7eedecf2a75eec2a8008991a82d0a61be844ab4b
384ae0bf2f5d7e15b0b60655693fd600b52c0f5bfcaa4ba7336d0ebeb224e84b99b597f77d26a1249e14a4e7bbc1629be00556b393bb9dd2266cb4bd67c3cfea 06_fix_mdss_fb_rgb_mode.patch
1f743d3e7f4ac7401167ea35edc7d7e113bd80824c4d53631d7500f33557ff486163f8244786c16506b2e21db6ccbcd8a0f7b26fcf4937efee50b62c074f9a22 07_fix_mdss_fb_refresh_rate.patch
f83e9b6549155a2f32c89dffbab3ad6fba7b8d93976dfccb1232833244ed6e064e28105a321eaa934c5bb326384730d03f3d3141227a7258a30045fa12573268 08_fix_touchscreen.patch
c9831aa037d4cb26fa349c44a27111daf8f7a84a9527d0221ecc4f01839b195243c178838663ff7592bb1d5c3cdc9872b449254beb7b9dffa67c365c3d8e042c 09_fix_various_include_directives.patch"
c9831aa037d4cb26fa349c44a27111daf8f7a84a9527d0221ecc4f01839b195243c178838663ff7592bb1d5c3cdc9872b449254beb7b9dffa67c365c3d8e042c 09_fix_various_include_directives.patch
b0b9bcea00ca4a79ea6d6a9e0b153559161a102b0856193c7d775318beeb1d4ffb194127bf8f94f006930dd7cd330c3185f9bd205fef39e9856ffe9019fc2a34 10_vfs-fix-proc-tid-fdinfo-fd-file-handling.patch"